Electric energy quality monitoring device and system

Abstract

The utility model discloses an electric energy quality monitoring device and system, which are used for carrying out electric energy monitoring on a new energy station, and the electric energy quality monitoring device comprises an electric energy quality monitor, at least one electronic voltage transformer and at least one electronic current transformer. The electronic voltage transformer is arranged at a preset voltage monitoring position of a cable corresponding to the electronic voltage transformer in a new energy station and is used for acquiring a three-phase voltage signal of the cable; the electronic current transformer is arranged at a preset current monitoring position of a cable corresponding to the electronic current transformer in a new energy station, and is used for collecting a three-phase current signal of the cable; the electric energy quality monitor is connected with each electronic voltage transformer and each electronic current transformer so as to acquire a three-phase voltage signal and a three-phase current signal. According to the technical scheme disclosed by the utility model, the number of secondary loop signal transmission lines in the electric energy quality monitoring system can be reduced, and the risk of line faults of the system is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of electric energy monitoring, in particular to an electric energy quality monitoring device and system. Background Art

[0002] The integration of a large number of renewable energy power systems into the power grid is bringing with it power quality issues, resulting in power generation equipment being unable to reliably deliver power to the grid. Furthermore, the increasing number of power electronic devices on the load side generates significant harmonics at the grid connection point, severely impacting the power quality of the entire grid. In renewable energy power systems, harmonics and other power quality influencing factors present a massive number of harmonic sources, coupled and superimposed, complicating power quality analysis. Currently, within renewable energy power stations, potential sources of harmonics or power quality issues include dynamic VAR compensation devices, wind turbines or photovoltaic inverters, collector lines, and the underlying power grid. The large number of wind turbines or photovoltaic inverters, coupled with the complex collector lines, amplifies or modifies power quality issues, further complicating power quality within renewable energy stations. Therefore, power quality monitoring at renewable energy stations is necessary. Currently, when conducting power quality monitoring, it is necessary to collect the three-phase voltage signals and three-phase current signals of specific cables in new energy stations to provide data support for the monitoring work.

[0003] At present, the existing power quality monitoring system includes a data sampling module, a power quality monitoring device and a host computer. The data sampling module uses an electromagnetic voltage transformer or a capacitive voltage transformer to collect the three-phase voltage signal of a specific cable, and uses an electromagnetic current transformer to collect the three-phase current signal of a specific cable. Here, when the electromagnetic voltage transformer or the capacitive voltage transformer collects the three-phase voltage, it is necessary to extend three cables to connect to the power quality monitoring device so as to send the collected voltage of each phase to the power quality monitoring device respectively; at the same time, when the electromagnetic current transformer collects the three-phase current, it is also necessary to extend three cables to connect to the power quality monitoring device so as to send the collected current of each phase to the power quality monitoring device respectively, so that the power quality monitoring device can obtain the above-mentioned three-phase voltage and three-phase current, providing data support for the power quality monitoring work.

[0004] However, when the existing power quality monitoring system is connected to a large number of voltage transformers and current transformers, each voltage transformer and current transformer needs to extend three cables to the power quality monitoring device, which leads to a large number of complex secondary circuit lines in the power quality monitoring system, and is prone to system line failures caused by open or short circuits in the secondary circuit, resulting in low monitoring reliability of the power quality monitoring system. Utility Model Content

[0005] In view of this, the present invention provides a power quality monitoring device and system, the main purpose of which is to solve the technical problem that the secondary circuit lines in the power quality monitoring system are numerous and complex, and line failures are prone to occur, which leads to low monitoring reliability of the power quality monitoring system.

[0006] To achieve the above objectives, the present invention first provides a power quality monitoring device for monitoring power at a new energy station. The power quality monitoring device includes a power quality monitor, at least one electronic voltage transformer, and at least one electronic current transformer.

[0007] The electronic voltage transformer is provided at a preset voltage monitoring position of a cable corresponding to the electronic voltage transformer in the new energy station, and is used to collect a three-phase voltage signal of the cable;

[0008] The electronic current transformer is provided at a preset current monitoring position of a cable corresponding to the electronic current transformer in the new energy station, and is used to collect a three-phase current signal of the cable;

[0009] The power quality monitor is connected to each of the electronic voltage transformers and each of the electronic current transformers respectively to obtain the three-phase voltage signal and the three-phase current signal.

[0010] In one embodiment of the present invention, the electronic voltage transformer is connected to the power quality monitor via a serial communication bus, and is used to send the three-phase voltage signal in the form of a digital signal to the power quality monitor; the electronic current transformer is connected to the power quality monitor via a serial communication bus, and is used to send the three-phase current signal in the form of a digital signal to the power quality monitor.

[0011] In one embodiment of the present invention, the power quality monitor has a remote communication interface, and the power quality monitor is used to connect to a remote host computer through the remote communication interface to establish a communication connection between the host computer and the power quality monitor.

[0012] In one embodiment of the present invention, the power quality monitor includes a signal synchronization circuit and a digital signal processing unit; the signal synchronization circuit is connected to the electronic voltage transformer and the electronic current transformer, respectively, for obtaining the three-phase voltage signal and the three-phase current signal, and performing signal synchronization processing on the three-phase voltage signal and the three-phase current signal; the digital signal processing unit is connected to the signal synchronization circuit to receive the three-phase voltage signal and the three-phase current signal after signal synchronization processing from the signal synchronization circuit.

[0013] In one embodiment of the present utility model, the power quality monitor also includes a signal conversion unit; the digital signal processing unit is connected to the signal conversion unit via a controller area network bus, and is used to establish a communication connection between the digital signal processing unit and the signal conversion unit via a controller area network bus signal; the signal conversion unit is used to convert the controller area network bus signal into a communication signal suitable for the transmission control protocol / interconnection protocol, and send the communication signal to the host computer through the remote communication interface; the signal conversion unit is also used to convert the communication signal suitable for the transmission control protocol / interconnection protocol received from the host computer into a controller area network bus signal, so as to establish a communication connection between the digital signal processing unit and the host computer.

[0014] In one embodiment of the present utility model, the digital signal processing unit includes a first digital signal processor and a second digital signal processor; the first digital signal processor is connected to the signal synchronization circuit to obtain the three-phase voltage signal and the three-phase current signal after signal synchronization processing; the first digital signal processor is also connected to the storage device access device, and is used to establish a communication connection between the first digital signal processor and the storage device when the storage device access device is connected to the storage device; the second digital signal processor is respectively connected to the first digital signal processor and the signal conversion unit.

[0015] In one embodiment of the present invention, the signal synchronization circuit includes a digital-to-analog converter, a phase-locked frequency multiplication circuit, and an analog-to-digital converter; the digital-to-analog converter obtains the three-phase voltage signal and the three-phase current signal from the electronic voltage transformer and the electronic current transformer respectively, and performs digital-to-analog conversion on the three-phase voltage signal and the three-phase current signal; the phase-locked frequency multiplication circuit is connected to the digital-to-analog converter, and is used to obtain the three-phase voltage signal in the form of an analog signal, and determine the voltage phase information of each phase voltage in the three-phase voltage signal; the phase-locked frequency multiplication circuit is also used to obtain the three-phase current signal in the form of an analog signal, and determine the current phase information of each phase current in the three-phase current signal; the analog The analog-to-digital converter is used to obtain the three-phase voltage signal in the form of an analog signal and the voltage phase information of each phase voltage in the three-phase voltage signal, and perform signal synchronization processing on the three-phase voltage signal based on the voltage phase information to obtain the phase-synchronized three-phase voltage signal, and send the phase-synchronized three-phase voltage signal to the digital signal processing unit; the analog-to-digital converter is also used to obtain the three-phase current signal in the form of an analog signal and the current phase information of each phase current in the three-phase current signal, and perform signal synchronization processing on the three-phase current signal based on the current phase information to obtain the phase-synchronized three-phase current signal, and send the phase-synchronized three-phase current signal to the digital signal processing unit.

[0016] In addition, to achieve the above-mentioned purpose, the present invention also proposes a power quality monitoring system, which includes the power quality monitoring device as described above.

[0017] In one embodiment of the present invention, the power quality monitoring system further includes a monitoring display device; the monitoring display device is connected to the power quality monitor in the power quality monitoring apparatus.

[0018] The utility model provides a power quality monitoring device and system, which can collect the three-phase voltage signal of the cable that needs to be monitored in the new energy station through an electronic voltage transformer, and can collect the three-phase current signal of the cable that needs to be monitored in the new energy station through an electronic current transformer. Here, the electronic voltage transformer can collect the three-phase voltage signal and convert the three-phase voltage signal into a three-phase voltage signal in the form of a digital signal, and then the three-phase voltage signal in the form of a digital signal can be connected to the power quality monitor through a cable, so that the power quality monitor receives the three-phase voltage signal. At the same time, the electronic current transformer can collect the three-phase current signal and convert the three-phase current signal into a three-phase current signal in the form of a digital signal, and then the three-phase current signal in the form of a digital signal can be connected to the power quality monitor through a cable, so that the power quality monitor receives the three-phase current signal. Compared with collecting three-phase voltage signals and three-phase current signals through traditional electromagnetic voltage transformers, capacitive voltage transformers and electromagnetic current transformers, electronic voltage transformers and electronic current transformers only need to extend one cable each to send three-phase current signals and three-phase voltage signals to the power quality monitor, which can significantly reduce the number of secondary circuit lines in the system, increase the number of signals that can be accessed by power quality monitoring, simplify line layout, and effectively avoid the probability of system line failures caused by open or short circuits in the secondary circuit, thereby effectively improving the reliability of power monitoring.

[0019] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0021] Figure 1 A schematic structural diagram of an existing power quality monitoring system provided by an embodiment of the present utility model is shown;

[0022] Figure 2 One of the structural diagrams of a power quality monitoring device provided by an embodiment of the present utility model is shown;

[0023] Figure 3 The second structural diagram of a power quality monitoring device provided by an embodiment of the present utility model is shown;

[0024] Figure 4 The third structural diagram of a power quality monitoring device provided by an embodiment of the present utility model is shown;

[0025] Figure 5 A structural diagram of a power quality monitoring system provided by an embodiment of the present utility model is shown. DETAILED DESCRIPTION

[0026] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other.

[0027] To further illustrate the technical means and effects employed by the present invention to achieve its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention is provided in conjunction with the accompanying drawings and preferred embodiments. In the following description, different references to "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0028] Currently, if Figure 1 As shown, the existing power quality monitoring system includes an electromagnetic voltage transformer, an electromagnetic current transformer, a power quality monitor, and a host computer. The electromagnetic voltage transformer is used to collect the three-phase voltage signal of a specific cable, and the electromagnetic current transformer is used to collect the three-phase current signal of a specific cable. Here, when collecting three-phase voltage, the electromagnetic voltage transformer or the capacitive voltage transformer needs to extend three cables to connect to the power quality monitoring device to send the collected voltage of each phase to the power quality monitoring device. At the same time, when collecting three-phase current, the electromagnetic current transformer also needs to extend three cables to connect to the power quality monitoring device to send the collected current of each phase to the power quality monitoring device, thereby providing data support for the power quality monitoring device to perform power quality monitoring tasks such as harmonic analysis. However, when the existing power quality monitoring system is connected to a large number of voltage transformers and current transformers, each voltage transformer and current transformer needs to extend three cables to the power quality monitoring device, which leads to a large number of complex secondary circuit lines in the power quality monitoring system, and is prone to system line failures caused by open or short circuits in the secondary circuit, resulting in low monitoring reliability of the power quality monitoring system.

[0029] In order to solve the above problems, the embodiments of the present application are combined with Figures 2 to 5 The present invention describes a power quality monitoring device and system according to some embodiments of the present invention.

[0030] like Figure 2As shown, an embodiment of the present invention proposes a power quality monitoring device for monitoring power at a new energy station. The power quality monitoring device includes a power quality monitor, at least one electronic voltage transformer and at least one electronic current transformer. Here, the electronic voltage transformer (EVT) is a device for measuring voltage in a high-voltage power system. Compared with traditional electromagnetic voltage transformers or capacitive voltage transformers, electronic voltage transformers have higher accuracy, lower load and a wider range of applications. It is mainly composed of a voltage divider module and a digital processing module. The high voltage signal is divided into a low voltage signal by a high-resistance resistor, and then amplified, filtered and digitized to output accurate voltage measurement results, and the measurement results are output to the outside in the form of digital signals.

[0031] Furthermore, an electronic current transformer (ECT) is an advanced current measurement device that uses electronics to measure and convert current. Compared to traditional electromagnetic CTs, ECTs offer advantages such as no magnetic saturation, high precision, and wideband response. They are suitable for energy metering, protection, and monitoring in power systems. They can collect current signals and output them as digital signals.

[0032] Specifically, the electronic voltage transformer is installed at a preset voltage monitoring position on the cable corresponding to the electronic voltage transformer in the new energy station to collect the three-phase voltage signal of the cable. Here, the cables requiring three-phase voltage collection can be pre-selected in the new energy station. These cables can be cables that output power to nodes such as wind turbines and inverters that generate harmonics or power quality issues, and the preset voltage monitoring position is determined on the cable based on actual conditions. Furthermore, an electronic voltage transformer is installed at each preset voltage monitoring position to collect three-phase voltage signals from the cable at each preset voltage monitoring position.

[0033] Furthermore, the electronic current transformer is installed at a preset current monitoring position on the cable corresponding to the electronic current transformer in the new energy station, and is used to collect the three-phase current signal of the cable. Here, the cable requiring three-phase current collection can be pre-selected in the new energy station. The cable can be a cable that outputs power to nodes such as wind turbines and inverters that generate harmonics or power quality problems, and the preset current monitoring position is determined on the cable based on actual conditions. Furthermore, an electronic current transformer is installed at each preset current monitoring position to collect three-phase current signals from the cable at each preset current monitoring position.

[0034] Furthermore, the power quality monitor is respectively connected to each of the electronic voltage transformers and each of the electronic current transformers to obtain the three-phase voltage signal and the three-phase current signal. The power quality monitor can be a computer device with certain computing functions, which can be connected to at least 54 electronic voltage transformers and electronic current transformers. Specifically, the power quality monitor can obtain the three-phase voltage signal collected by each electronic voltage transformer and the three-phase current signal collected by each electronic current transformer through data round-robin training, and summarize and store the obtained three-phase voltage signal and three-phase current signal. Here, the power quality monitor completes the real-time and accurate data collection of the three-phase voltage and three-phase current of each node in the entire new energy station system, so as to provide reliable data resources for the subsequent calculation and analysis of various power quality indicators.

[0035] Furthermore, the power quality monitor can also send the three-phase voltage signal and the three-phase current signal to the remote host computer for harmonic monitoring, so that the host computer can perform harmonic monitoring and other power quality monitoring work on the new energy station based on the three-phase voltage signal and the three-phase current signal. Furthermore, the host computer central management host mainly completes the work of data reception, analysis of various power quality disturbances, database storage and human-computer interaction interface. The main contents are as follows: (1) The data reception part of the host computer realizes communication and transmission with the power quality monitoring device. It adopts two transmission methods, serial port and network port, to realize real-time data reception respectively, and includes error correction function to ensure the quality of data collection. (2) The power quality disturbance analysis part of the host computer can perform power quality analysis on the collected data according to the corresponding national standards, and can use FFT, Dyn measurement and RMS algorithm to accurately identify power quality disturbances and calculate their characteristic quantities. (3) The database part of the host computer writes real-time data, various disturbance data and characteristic quantities into the database. And design a human-computer interface to realize the operation of the database. (4) The human-computer interaction interface of the host computer mainly includes the design of the login interface, the drawing of real-time waveform curves, and the calculation and waveform display of various parameters of single electric energy signals.

[0036] Furthermore, a related power monitoring program can also be set in the power quality monitor to realize power quality monitoring such as harmonic monitoring of the new energy station based on the three-phase voltage signal and the three-phase current signal.

[0037] It should be noted that the internal circuit connection method of the power quality monitor, electronic voltage transformer, and electronic current transformer can be determined according to actual conditions, and this embodiment does not make specific restrictions. In addition, the connection method of each device can be determined according to the specific selection of the device, and this embodiment does not make specific restrictions. The circuit function of the power quality monitoring device provided in this embodiment is mainly realized through the circuit connection relationship between each circuit module, and does not rely on the program module in a certain circuit module. In addition, for a power quality monitor that can be implanted with a program module, the realization of its module function can be achieved through the program module provided by the existing technology.

[0038] The power quality monitoring device proposed in the embodiment of the present utility model can collect the three-phase voltage signal of the cable that needs to be monitored in the new energy station through the electronic voltage transformer, and can collect the three-phase current signal of the cable that needs to be monitored in the new energy station through the electronic current transformer. Here, the electronic voltage transformer can collect the three-phase voltage signal and convert the three-phase voltage signal into a three-phase voltage signal in the form of a digital signal. The three-phase voltage signal in the form of a digital signal can be connected to the power quality monitor through a cable so that the power quality monitor receives the three-phase voltage signal. At the same time, the electronic current transformer can collect the three-phase current signal and convert the three-phase current signal into a three-phase current signal in the form of a digital signal. The three-phase current signal in the form of a digital signal can be connected to the power quality monitor through a cable so that the power quality monitor receives the three-phase current signal. Compared with collecting three-phase voltage signals and three-phase current signals through traditional electromagnetic voltage transformers, capacitive voltage transformers and electromagnetic current transformers, electronic voltage transformers and electronic current transformers only need to extend one cable each to send three-phase current signals and three-phase voltage signals to the power quality monitor, which can significantly reduce the number of secondary circuit lines in the system, simplify the line layout, and effectively avoid the probability of system line failures caused by open or short circuits in the secondary circuit, thereby effectively improving the reliability of power monitoring.

[0039] In one embodiment, the electronic voltage transformer is connected to the power quality monitor via a serial communication bus, and is used to send the three-phase voltage signal in the form of a digital signal to the power quality monitor. Furthermore, the electronic current transformer is connected to the power quality monitor via a serial communication bus, and is used to send the three-phase current signal in the form of a digital signal to the power quality monitor. Here, the serial communication bus can be an RS485 transmission line or a TS232 transmission line, wherein the RS485 transmission line can use a 0.5mm twisted pair shielded wire, and the wire impedance can be 120Ω. The RS485 transmission line cannot use parallel wires to better transmit digital signals.

[0040] Specifically, each electronic voltage transformer can be connected to the power quality monitor via a serial communication bus to send the collected three-phase voltage signal to the power quality monitor. Furthermore, each electronic current transformer can be connected to the power quality monitor via a serial communication bus to send the collected three-phase current signal to the power quality monitor. The embodiment provided by the present application can connect the electronic voltage transformer and the electronic current transformer to the power quality monitor through a standard serial port communication method, thereby improving the long-distance transmission capability of the signal, thereby enhancing the signal quality of the three-phase voltage signal and the three-phase current signal obtained by the power quality monitoring device, and improving the power quality monitoring capability of the power quality monitoring device.

[0041] In one embodiment, the power quality monitor has a remote communication interface, and the power quality monitor is used to be connected to a remote host computer through the remote communication interface to establish a communication connection between the host computer and the power quality monitor. The host computer can be a remote computer terminal. Here, the remote communication interface can be an optical fiber interface or an Ethernet cable interface, so that the power quality monitor can establish a communication connection with the host computer through the Ethernet communication method of the Transmission Control Protocol / Internet Protocol (TCP / IP). Here, since Ethernet has the characteristics of high reliability, fast transmission speed and simple connection method, this device selects Ethernet as the main communication method. The protocol used is the commonly used Ethernet standard protocol, which can realize high-speed data transmission between the central management computer and the monitoring point. This communication method has a high transmission rate, and its transmission medium is a cable or optical fiber.

[0042] The embodiment provided by the present application enables relevant staff to remotely control the power quality monitoring device through the host computer. At the same time, the power quality monitor can also send the collected three-phase voltage signals and three-phase current signals of each node of the new energy station to the host computer, so that the host computer can perform power quality monitoring and analysis on the new energy station based on the three-phase voltage signals and three-phase current signals. Furthermore, the power quality monitor can also perform power quality monitoring and analysis on the new energy station based on the three-phase voltage signals and three-phase current signals, and send the monitoring and analysis results to the host computer, so that relevant staff can promptly know the power quality status of the new energy station, thereby improving the operability of the power quality monitoring device.

[0043] In one embodiment, Figure 3As shown, the power quality monitor includes a signal synchronization circuit and a digital signal processing unit. Specifically, the signal synchronization circuit is connected to each of the electronic voltage transformers and each of the electronic current transformers, respectively, for obtaining the three-phase voltage signal and the three-phase current signal, and performing signal synchronization processing on the three-phase voltage signal and the three-phase current signal; here, the signal synchronization circuit is used to synchronize the three-phase voltage signal received from each electronic voltage transformer, so that the zero moment of each phase voltage signal in each three-phase voltage signal is at the same position. Furthermore, the signal synchronization circuit is used to synchronize the three-phase current signal received from each electronic current transformer, so that the zero moment of each phase current signal in each three-phase current signal is at the same position.

[0044] Furthermore, the digital signal processing unit is connected to the signal synchronization circuit to receive the three-phase voltage signal and the three-phase current signal after signal synchronization processing from the signal synchronization circuit. The digital signal processing unit can be a device with certain computing capabilities, such as a single-chip microcomputer or a digital signal processor. Specifically, the digital signal processing unit can receive the three-phase voltage signal and the three-phase current signal after signal synchronization processing from the signal synchronization circuit. The digital signal processing unit can send the above-mentioned three-phase voltage signal and three-phase current signal to the host computer, so that the host computer can perform power quality monitoring such as harmonic monitoring on the new energy station based on the three-phase voltage signal and the three-phase current signal. Furthermore, a related power monitoring program can also be set in the power quality monitor to realize power quality monitoring such as harmonic monitoring on the new energy station based on the three-phase voltage signal and the three-phase current signal, and send the monitoring results to the host computer.

[0045] The embodiment provided in the present application can collect three-phase voltage signals from each electronic voltage transformer in a round-robin manner through a signal synchronization circuit, and collect three-phase current signals from each electronic current transformer in a round-robin manner, and synchronize the above signals, and send the synchronized three-phase voltage signals and three-phase current signals to a digital signal processing unit for subsequent processing, thereby improving the signal acquisition capability of the power quality monitoring device.

[0046] In one embodiment, Figure 4 As shown, the power quality monitor further includes a signal conversion unit. The signal conversion unit is used to convert between Controller Area Network (CAN) signals and communication signals applicable to the Ethernet protocol. The communication signals applicable to the Ethernet protocol here can be communication signals applicable to the TCP / IP protocol.

[0047] Specifically, the digital signal processing unit and the signal conversion unit are connected via a controller area network (CAN) bus, and are configured to establish a communication connection between the digital signal processing unit and the signal conversion unit via CAN bus signals, so that the digital signal processing unit can send CAN bus signals to the signal conversion unit, and the signal conversion unit can also send CAN bus signals to the digital signal processing unit. The CAN bus signals can be signals related to the interaction between the power quality monitoring device and the host computer, including control signals from the host computer to the power quality monitoring device, data sent from the host computer to the power quality monitoring device, and monitoring signals sent from the power quality monitoring device to the host computer, including monitoring results, three-phase voltage signals, and three-phase current signals.

[0048] Furthermore, the signal conversion unit is used to convert the controller area network bus signal into a communication signal suitable for the TCP / IP protocol, and send the communication signal to the host computer via the remote communication interface. Furthermore, the signal conversion unit is also used to convert the communication signal suitable for the TCP / IP protocol received from the host computer into a controller area network bus signal, so as to establish a communication connection between the digital signal processing unit and the host computer. In the embodiment provided by the present application, the controller area network bus signal suitable for the digital signal processing unit can be converted into a communication signal of the TCP / IP protocol suitable for the host computer by the signal conversion unit, so as to realize data communication between the host computer and the digital signal processing unit, thereby improving the data interaction capability of the power quality monitoring device.

[0049] In one embodiment, Figure 4 As shown, the power quality monitor also includes a storage device access device, which is used to access an external storage device; wherein the storage device access device is a Universal Serial Bus (USB) access device, which can have a USB interface to connect to storage media such as a USB flash drive.

[0050] Furthermore, the storage device access device is connected to the digital signal processing unit and is used to establish a communication connection between the storage device and the digital signal processing unit when the storage device access device is connected to the storage device. The embodiment provided by the present application can enable the power quality monitoring device to store the collected three-phase current signal and three-phase voltage signal in the storage device, so that in the subsequent processing process, the relevant staff can connect the storage device storing the three-phase current signal and the three-phase voltage signal to the host computer, so that the host computer can obtain the three-phase current signal and the three-phase voltage signal for power quality monitoring or other operations; further, the power quality monitoring device can also be enabled to store the obtained power quality monitoring results in the storage device, so that the relevant staff can easily obtain the power quality monitoring results; further, the relevant data required for the power quality monitoring device to perform power quality monitoring can also be stored in the storage device, and the storage device can be connected to the power quality monitoring device, so that the power quality monitoring device can easily obtain the above-mentioned relevant data, thereby improving the operability of the power quality monitoring device.

[0051] In the actual power monitoring process, the power quality monitoring device may need to obtain relevant data for power quality monitoring from the outside world, such as the motor type of the new energy station, the circuit topology diagram, and the relevant parameters of the grid system connected to the grid, and combine the three-phase voltage signal and the three-phase current signal to perform power quality monitoring. Here, the above-mentioned relevant data can be stored in a storage device in advance, and the storage device can be connected to the storage device access device so that the digital signal processing unit can obtain the relevant data and perform power quality monitoring based on the three-phase voltage signal, the three-phase current signal and the related data. Furthermore, the above-mentioned relevant data can also be sent to the digital signal processing unit through the host computer so that the digital signal processing unit can obtain the relevant data and perform power quality monitoring based on the three-phase voltage signal, the three-phase current signal and the related data.

[0052] In view of the above situation, in one embodiment, Figure 4 As shown, the digital signal processing unit includes a first digital signal processor and a second digital signal processor. Here, the first digital signal processor and the second digital signal processor can be respectively provided with programs related to power quality monitoring to perform power quality monitoring work.

[0053] Specifically, the first digital signal processor is connected to the signal synchronization circuit to obtain the three-phase voltage signal and the three-phase current signal after signal synchronization processing; further, the first digital signal processor is also connected to the storage device access device, and is used to establish a communication connection between the first digital signal processor and the storage device when the storage device access device is connected to the storage device, so as to obtain relevant data pre-stored in the storage device from the storage device. Furthermore, when it is necessary to obtain relevant data from the storage device to perform power quality monitoring in combination with the three-phase voltage signal and the three-phase current signal after signal synchronization processing, the first digital signal processor can obtain the relevant data, the three-phase voltage signal and the three-phase current signal, and perform power quality monitoring based on the relevant data, the three-phase voltage signal and the three-phase current signal to obtain power quality monitoring results, and the power quality monitoring results can be sent to the host computer via the second numerical processor and the signal conversion unit.

[0054] Furthermore, the second digital signal processor is connected to the first digital signal processor and the signal conversion unit, respectively. When it is necessary to obtain relevant data from the host computer to perform power quality monitoring in combination with the three-phase voltage signal and the three-phase current signal after signal synchronization processing, the second digital signal processor can obtain the relevant data from the host computer, and obtain the three-phase voltage signal and the three-phase current signal after signal synchronization processing from the signal synchronization circuit via the first digital signal processor. Furthermore, the second digital signal processor performs power quality monitoring based on the relevant data, the three-phase voltage signal, and the three-phase current signal to obtain the power quality monitoring results, and can send the power quality monitoring results to the host computer via the signal conversion unit.

[0055] The embodiments provided in the present application can respectively perform power quality monitoring by a first digital signal processor and a second digital signal processor according to different methods of obtaining relevant data, thereby reducing the computational pressure of a single digital signal processor and improving the efficiency of power quality monitoring.

[0056] In an optional embodiment, if Figure 4As shown, the signal synchronization circuit includes a digital-to-analog converter, a phase-locked frequency multiplication circuit and an analog-to-digital converter; wherein the existing phase-locked frequency multiplication circuit can be composed of four parts: a phase comparator, a loop filter, a voltage-controlled oscillator and a frequency divider. The working principle of the circuit is: for a three-phase voltage signal, the input three-phase voltage signal can be used as an input signal, and after the phase comparator of the phase-locked frequency multiplication circuit and the phase of the phase-locked loop are locked, the phase of each phase voltage signal in the three-phase voltage signal is obtained as an output signal; further, for a three-phase current signal, the input three-phase current signal can be used as an input signal, and after the phase comparator of the phase-locked frequency multiplication circuit and the phase of the phase-locked loop are locked, the phase of each phase current signal in the three-phase current signal is obtained as an output signal.

[0057] Specifically, the digital-to-analog converter obtains the three-phase voltage signal and the three-phase current signal from the electronic voltage transformer and the electronic current transformer, respectively, and performs digital-to-analog conversion on the three-phase voltage signal and the three-phase current signal. Specifically, the digital-to-analog converter can be connected to each electronic voltage transformer and each electronic current transformer, respectively, to obtain the three-phase voltage signal collected by each electronic voltage transformer and the three-phase current signal collected by each electronic current transformer in a patrol manner. Here, the three-phase voltage signal and three-phase current signal output by the electronic voltage transformer and the electronic current transformer exist in the form of digital signals and need to be converted into analog signals before the three-phase voltage signal and the three-phase current signal can be synchronously processed.

[0058] Furthermore, the phase-locked frequency multiplication circuit is connected to the digital-to-analog converter, and is used to obtain the three-phase voltage signal in the form of an analog signal, and determine the voltage phase information of each phase voltage in the three-phase voltage signal; the phase-locked frequency multiplication circuit is also used to obtain the three-phase current signal in the form of an analog signal, and determine the current phase information of each phase current in the three-phase current signal; specifically, for the three-phase voltage signal corresponding to each electronic voltage transformer, the phase-locked frequency multiplication circuit can determine the voltage phase information of the voltage signal of each phase; further, for the three-phase current signal corresponding to each electronic current transformer, the phase-locked frequency multiplication circuit can determine the current phase information of the current signal of each phase.

[0059] Furthermore, the analog-to-digital converter is used to obtain the three-phase voltage signal in the form of an analog signal and the voltage phase information of each phase voltage in the three-phase voltage signal, and perform signal synchronization processing on the three-phase voltage signal based on the voltage phase information to obtain the phase-synchronized three-phase voltage signal, and send the phase-synchronized three-phase voltage signal to the digital signal processing unit; specifically, for the three-phase voltage signal corresponding to each electronic voltage transformer, the analog-to-digital converter obtains the three-phase voltage signal from the digital-to-analog converter, and obtains the voltage phase information of the voltage signal of each phase of the three-phase voltage signal from the phase-locked frequency multiplication circuit, and then performs signal synchronization processing on the voltage signal of each phase of the three-phase voltage signal to obtain the three-phase voltage signal after signal synchronization processing.

[0060] Furthermore, the analog-to-digital converter is also used to obtain the three-phase current signal in the form of an analog signal and the current phase information of each phase current in the three-phase current signal, and perform signal synchronization processing on the three-phase current signal based on the current phase information to obtain the phase-synchronized three-phase current signal, and send the phase-synchronized three-phase current signal to the digital signal processing unit. Specifically, for the three-phase current signal corresponding to each electronic current transformer, the analog-to-digital converter obtains the three-phase current signal from the digital-to-analog converter, obtains the current phase information of each phase current signal of the three-phase current signal from the phase-locked frequency multiplication circuit, and then performs signal synchronization processing on the current signal of each phase of the three-phase current signal to obtain the three-phase current signal after signal synchronization processing.

[0061] The embodiments provided in the present application can perform signal synchronization processing on the three-phase voltage signal corresponding to each electronic voltage transformer based on a digital-to-analog converter, a phase-locked frequency multiplication circuit, and an analog-to-digital converter, and can perform signal synchronization processing on the three-phase current signal corresponding to each electronic current transformer, so that the digital signal processing unit can summarize and store the synchronized three-phase voltage signal and three-phase current signal, provide data support for subsequent power quality monitoring work, and improve the power quality monitoring capability of the power quality monitoring device.

[0062] On the other hand, an embodiment of the present invention provides a power quality monitoring system, which includes the power quality monitoring device as described above.

[0063] In an optional embodiment, if Figure 5 As shown, the power quality monitoring system further includes a monitoring display device, wherein the monitoring display device can be a computer terminal with a data display function.

[0064] Specifically, the monitoring display device is connected to the power quality monitor in the power quality monitoring device, and the power quality monitor can send the collected three-phase current signal and three-phase voltage signal to the monitoring display device.

[0065] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present utility model patent shall be determined by the appended claims.

Claims

1. A power quality monitoring device for monitoring power quality at a new energy station, characterized in that: The power quality monitoring device includes a power quality monitor, at least one electronic voltage transformer and at least one electronic current transformer; The electronic voltage transformer is provided at a preset voltage monitoring position of the cable corresponding to the electronic voltage transformer in the new energy station, and is used to collect the three-phase voltage signal of the cable; The electronic current transformer is provided at a preset current monitoring position of a cable corresponding to the electronic current transformer in the new energy station, and is used to collect a three-phase current signal of the cable; The power quality monitor is connected to each of the electronic voltage transformers and each of the electronic current transformers respectively to obtain the three-phase voltage signal and the three-phase current signal.

2. The power quality monitoring device according to claim 1, characterized in that: The electronic voltage transformer is connected to the power quality monitor via a serial communication bus, and is used to send the three-phase voltage signal in the form of a digital signal to the power quality monitor; The electronic current transformer is connected to the power quality monitor via a serial communication bus, and is used to send the three-phase current signal in the form of a digital signal to the power quality monitor.

3. The power quality monitoring device according to claim 1, characterized in that: The power quality monitor has a remote communication interface, and the power quality monitor is used to connect to a remote host computer through the remote communication interface to establish a communication connection between the host computer and the power quality monitor.

4. The power quality monitoring device according to claim 3, characterized in that: The power quality monitor includes a signal synchronization circuit and a digital signal processing unit; The signal synchronization circuit is connected to the electronic voltage transformer and the electronic current transformer respectively, and is used to obtain the three-phase voltage signal and the three-phase current signal, and perform signal synchronization processing on the three-phase voltage signal and the three-phase current signal; The digital signal processing unit is connected to the signal synchronization circuit to receive the three-phase voltage signal and the three-phase current signal after signal synchronization processing from the signal synchronization circuit.

5. The power quality monitoring device according to claim 4, characterized in that: The power quality monitor further includes a signal conversion unit; The digital signal processing unit is connected to the signal conversion unit via a controller area network bus, and is used to establish a communication connection between the digital signal processing unit and the signal conversion unit via a controller area network bus signal; The signal conversion unit is used to convert the controller area network bus signal into a communication signal suitable for the transmission control protocol / interconnection protocol, and send the communication signal to the host computer through the remote communication interface; The signal conversion unit is further configured to convert the communication signal adapted for the transmission control protocol / interconnection protocol received from the host computer into a controller area network bus signal, so as to establish a communication connection between the digital signal processing unit and the host computer.

6. The power quality monitoring device according to claim 5, characterized in that: The power quality monitor further includes a storage device access device, wherein the storage device access device is used to access an external storage device; The storage device access device is connected to the digital signal processing unit and is used to establish a communication connection between the storage device and the digital signal processing unit when the storage device access device is connected to the storage device.

7. The power quality monitoring device according to claim 6, characterized in that: The digital signal processing unit includes a first digital signal processor and a second digital signal processor; The first digital signal processor is connected to the signal synchronization circuit to obtain the three-phase voltage signal and the three-phase current signal after signal synchronization processing; The first digital signal processor is further connected to the storage device access device, and is used to establish a communication connection between the first digital signal processor and the storage device when the storage device access device is connected to the storage device; The second digital signal processor is connected to the first digital signal processor and the signal conversion unit respectively.

8. The power quality monitoring device according to claim 4, characterized in that: The signal synchronization circuit includes a digital-to-analog converter, a phase-locked frequency multiplication circuit and an analog-to-digital converter; The digital-to-analog converter obtains the three-phase voltage signal and the three-phase current signal from the electronic voltage transformer and the electronic current transformer respectively, and performs digital-to-analog conversion on the three-phase voltage signal and the three-phase current signal; The phase-locked frequency multiplication circuit is connected to the digital-to-analog converter and is used to obtain the three-phase voltage signal in the form of an analog signal and determine the voltage phase information of each phase voltage in the three-phase voltage signal; the phase-locked frequency multiplication circuit is also used to obtain the three-phase current signal in the form of an analog signal and determine the current phase information of each phase current in the three-phase current signal; The analog-to-digital converter is used to obtain the three-phase voltage signal in the form of an analog signal and voltage phase information of each phase voltage in the three-phase voltage signal, and perform signal synchronization processing on the three-phase voltage signal based on the voltage phase information to obtain the phase-synchronized three-phase voltage signal, and send the phase-synchronized three-phase voltage signal to the digital signal processing unit; The analog-to-digital converter is also used to obtain the three-phase current signal in the form of an analog signal and the current phase information of each phase current in the three-phase current signal, and perform signal synchronization processing on the three-phase current signal based on the current phase information to obtain the phase-synchronized three-phase current signal, and send the phase-synchronized three-phase current signal to the digital signal processing unit.

9. A power quality monitoring system, characterized in that: The power quality monitoring system includes the power quality monitoring device according to any one of claims 1 to 8.

10. The power quality monitoring system according to claim 9, characterized in that: The power quality monitoring system also includes a monitoring display device; The monitoring and display device is connected to the power quality monitor in the power quality monitoring apparatus.

Images